Sam Dawson (Sean Penn) is a developmentally disabled adult who has been singularly raising his daughter, Lucy for all of her seven years. Sam provides a fun and loving environment for Lucy, but it soon becomes apparent that she is intellectually surpassing him. When she begins intentionally stunting her own growth so as not to hurt her beloved father, a social worker intervenes, removing Lucy from her home and placing her in foster care. It is now up to the courts to decide if Sam is fit to continue raising Lucy. As the day of the hearing looms, Sam seeks the aid of self-absorbed, successful lawyer Rita Harrison (Michelle Pfeiffer), who only agrees to take on Sam's case free of charge to save face with her colleagues. And so it begins: a battle of love versus ability, the individual against an unbending system. In the centre remains a father and daughter who just want to be together.